This invention is directed to mechanisms for maintaining the operability of pens that are used for ink-jet printing.
Pens used with advanced ink-jet printers include print heads that have orifice plates formed with very small nozzles through which are fired ink drops. The drops are sized and fired for high-resolution printing. The ink used with such pens dries quickly, thereby enabling the printer to use plain paper.
The combination of small nozzles with quick-drying ink makes the pen print head susceptible to failure in the event that some or all of the nozzles become clogged with dried ink or minute dust particles, such as paper fibers.
An ink-jet printer manufactured by Hewlett-Packard Company and designated the "DeskJet" printer includes a service station assembly that features a mechanism for capping the print head nozzles when the pen is not printing. The cap mechanism encloses the exposed outer surface of the orifice plate to prevent drying of the ink near the nozzles. The cap also protects the nozzles from contact with dust. The service station assembly includes a wiper mechanism for wiping away particles that may accumulate on the orifice plate during printing. The service station assembly also includes a receptacle into which the pen periodically fires to purge dried or plugged nozzles.